Luiz Angelo Vieira

Clinical repercussions of Martin-Gruber anastomosis: anatomical study

Objective The main objective of this study was to describe Martin-Gruber anastomosis anatomically and to recognize its clinical repercussions. Method 100 forearms of 50 adult cadavers were dissected in an anatomy laboratory. The dissection was performed by means of a midline incision along the entire forearm and the lower third of the upper arm. Two flaps including skin and subcutaneous tissue were folded back on the radial and ulnar sides, respectively. Results Nerve communication between the median and ulnar nerves in the forearm (Martin-Gruber anastomosis) was found in 27 forearms. The anastomosis was classified into six types: type I: anastomosis between the anterior interosseous nerve and the ulnar nerve (n = 9); type II: anastomosis between the anterior interosseous nerve and the ulnar nerve at two points (double anastomosis) (n = 2); type III: anastomosis between the median nerve and the ulnar nerve (n = 4); type IV: anastomosis between branches of the median nerve and ulnar nerve heading toward the flexor digitorum profundus muscle of the fingers; these fascicles form a loop with distal convexity (n = 5); type V: intramuscular anastomosis (n = 5); and type VI: anastomosis between a branch of the median nerve to the flexor digitorum superficialis muscle and the ulnar nerve (n = 2). Conclusion Knowledge of the anatomical variations relating to the innervation of the hand has great importance, especially with regard to physical examination, diagnosis, prognosis and surgical treatment. If these variations are not given due regard, errors and other consequences will be inevitable.

Anastomose de Riché‐Cannieu: estrutura, função e significância clínica

Objective  To define the anatomy pattern and the incidence of Riché-Cannieu anastomosis, that is, median and ulnar communication in the palmar aspect of the hand. Materials Methods  A total of 80 anatomical dissections were performed on 60 hands of 30 cadavers from 1979 to 1982, and on 20 hands from 2012 to 2015. All of these procedures were performed at the Department of Anatomy of our institution. The incidence of Riché-Cannieu anastomosis and the innervation of the thenar muscles were studied. Results  Riché-Cannieu anastomosis was identified in every dissected hand (100%). The extramuscular Riché-Cannieu anastomosis was recorded in 57 hands, and the intramuscular, in 19 hands. The association of extra- and intramuscular Riché-Cannieu anastomoses occurred in four hands. The ulnar component always originated from the deep branch. The anastomotic branch arising from the median nerve originated from the motor thenar branch (recurrent branch) of the median nerve in most of the observations. The median-ulnar double innervation only to the deep head of the flexor pollicis brevis was identified in 29 of 80 hands. The double innervation only of the superficial head of the flexor pollicis brevis was found in 13 hands. In 12 hands, the deep head of the flexor pollicis brevis was absent. The double innervation of the superficial and deep heads of the flexor pollicis brevis occurred in 14 hands. The oblique head of the adductor pollicis received double innervation in 12 hands. The deep head of the flexor pollicis brevis and the oblique head of adductor pollicis were doubly-innervated in nine hands. The transverse head of the adductor pollicis received double innervation in two hands. Double innervation of the deep head of the flexor pollicis brevis and the transverse head of the adductor pollicis were found in one hand. Conclusion  According to the present study, Riché-Cannieu anastomosis should be considered a normal anatomical neural connection, not an anatomical variation. Knowledge of this anastomosis is essential because the presence of such neural communication may result in confusing clinical, surgical, and electromyographic findings in cases of median or ulnar damage or entrapment.

Anterior interosseous nerve: anatomical study and clinical implications

Objective The goal of this study was to describe anatomical variations and clinical implications of anterior interosseous nerve. In complete anterior interosseous nerve palsy, the patient is unable to flex the distal phalanx of the thumb and index finger; in incomplete anterior interosseous nerve palsy, there is less axonal damage, and either the thumb or the index finger are affected. Methods This study was based on the dissection of 50 limbs of 25 cadavers, 22 were male and three, female. Age ranged from 28 to 77 years, 14 were white and 11 were non-white; 18 were prepared by intra-arterial injection of a solution of 10% glycerol and formaldehyde, and seven were freshly dissected cadavers. Results The anterior interosseous nerve arose from the median nerve, an average of 5.2 cm distal to the intercondylar line. In 29 limbs, it originated from the nerve fascicles of the posterior region of the median nerve and in 21 limbs, of the posterolateral fascicles. In 41 limbs, the anterior interosseous nerve positioned between the humeral and ulnar head of the pronator teres muscle. In two limbs, anterior interosseous nerve duplication was observed. In all members, it was observed that the anterior interosseous nerve arose from the median nerve proximal to the arch of the flexor digitorum superficialis muscle. In 24 limbs, the branches of the anterior interosseous nerve occurred proximal to the arch and in 26, distal to it. Conclusion The fibrous arches formed by the humeral and ulnar heads of the pronator teres muscle, the fibrous arch of the flexor digitorum superficialis muscle, and the Gantzer muscle (when hypertrophied and positioned anterior to the anterior interosseous nerve), can compress the nerve against deep structures, altering its normal course, by narrowing its space, causing alterations longus and flexor digitorum profundus muscles.

Bicipital aponeurosis. Anatomical study and clinical implications

Objective The aim of this study was to analyze the anatomic variations of the bicipital aponeurosis (BA) (lacertus fibrosus) and its implications for the compression of the median nerve, which is positioned medially to the brachial artery, passing under the bicipital aponeurosis. Methods Sixty upper limbs of 30 cadavers were dissected, 26 of which were male and four, female; of the total, 15 had been previously preserved in formalin and glycerine and 15 were dissected fresh in the Laboratory of Anatomy. Results In 55 limbs, short and long heads of the biceps muscle contributed to the formation of the BA, and the most significant contribution was always from the short head. In three limbs, only the short head contributed to the formation of the BA. In two limbs, the BA was absent. The length of the bicipital aponeurosis from its origin to its insertion ranged from 4.5 to 6.2 cm and its width, from 0.5 to 2.6 cm. In 42 limbs, the BA was thickened; of these, in 27 it was resting directly on the median nerve, and in 17 a high insertion of the humeral head of the pronator teres muscle was found, and the muscle was interposed between the BA and the median nerve. Conclusion These results suggest that a thickened BA may be a potential factor for nerve compression, by narrowing the space through which the median nerve passes.

Palmar Cutaneous Branch of Median Nerve: An Anatomical Study

The purpose of this study was to determine the origin, frequency and anatomical variations of the palmar cutaneous branch of the median nerve (PCBMN) and its clinical implications in surgical procedures such as decompression of the carpal tun nel and volar approach to the wrist. Dissection of 30 forearms from 18 adult male specimens (9 bilateral, 7 right limbs and 5 left limb s) were performed using 2.5X magnification loupe in order to better understand the PCBMN. Origin, number, length, positioning, anatomic al relations and variations were recorded and analyzed. The PCBMN was identified in all dissected forearms, being the most distal branch of the median nerve in all forearms. The average origin was 4.8 cm (ranging 3.8 to 6.5 cm) proximal to the wrist flexion crease . Anatomical variations of the PCBMN are not rare and could endanger the nerve during surgical approach for the volar wrist and p rox m l palm. We did not find the PCBMN positioned ulnar to the fourth metacarpal axis as well as radial to the flexor carpi radialis t endon.

TRANSFER OF NERVE BRANCHES OF THE FLEXOR CARPI RADIALIS TO THE POSTERIOR INTEROSSEOUS NERVE

ABSTRACT Objective: The objective of this paper was to study the anatomical variations of the flexor carpi radialis muscle (FCR) and determine in cadaver limbs whether the FCR nervous branch can be connected to the posterior interosseous nerve (PIN) without tension and how close to the target muscles the transfer can be performed. Method: Thirty cadaveric upper limbs were dissected. Results: The FCR received exclusive innervation of the median nerve, distally to the intercondylar line of the humerus. In 5 limbs, an isolated branch was found and in 25, a common trunk with other nervous branches occurred. We investigated whether the branch for the FCR was long enough to be transferred to the PIN. The diameter of the nerve branch for the FCR corresponded on average to 50% of the PIN. Conclusion: In 12 limbs, the branch destined to the FCR could be connected to the PIN, distally to the nerve branches to the supinator muscle even during the movements of the forearm and the elbow. In 18 specimens, it was necessary to mobilize the PIN for this innervation. Level of Evidence IV, Case Series.

ARCADE OF FLEXOR DIGITORUM SUPERFICIALIS MUSCLE: ANATOMICAL STUDY AND CLINICAL IMPLICATIONS

ABSTRACT Objective: The arcade of the flexor digitorum superficialis muscle (FDS) is an anatomical structure which has not yet been widely studied and is a site of nerve compression. The aim of this study was to analyze the arcade of the FDS muscle and its relations with the median and anterior interosseous nerves through anatomic dissections. Method: Fifty arms from 25 adult cadavers (21 males and 4 females) were dissected; 18 were previously preserved in formalin and glycerin and 7 fresh specimens were dissected in the Laboratory of Anatomy. Results: The arcade of the superficial flexor muscle was identified in all dissected limbs. The radial and humeral heads were present in all specimens, and the ulnar head in 16 (32%). We identified two varieties of the arcade structure: a fibrous arcade in 32 specimens (64%), and a muscular arcade in 11 specimens (22%). In 4 specimens (8%) the arcade was very fine and so transparent that the nerve could be seen within the arcade. In 3 forearms the arcade was considered irregular because of discontinuity between the fibers that comprised this structure. Conclusion: The fibrous arcade of the FDS muscle may be a potential cause of nerve compression of the median and interosseous anterior nerves. Level of Evidence IV; Case series.

Flexor Pollicis Brevis Muscle. Anatomical Study and Clinical Implications

Introduction: This paper reports anatomical study of nature, incidence, innervation and clinical implications of Flexor Pollicis Brevis muscle (FPB). Material and Methods: The anatomical dissection of 60 limbs from 30 cadavers were performed in the Department of Anatomy of Medical School of Catholic University of São Paulo. Results: The superficial head of FPB has been innervated by the median nerve in 70% and in 30% it had double innervation. The deep head of FPB were absent in 14%, in 65%, occurred a double innervation. In 17.5% by deep branch of ulnar nerve and in 3.6% by recurrent branch of median nerve. Conclusion: The pattern of innervation more frequent in relationship to the flexor pollicis brevis muscle and should be considered as a normal pattern is that superficial head receives innervation of branches of median nerve and the deep head receives innervation of ulnar and median nerve.

The arcade of Struthers: an anatomical study and clinical implications☆

Objective To determine the frequency and features of the arcade of Struthers, and to assess its clinical implication in ulnar nerve compression. Method Forty arms from 26 cadaver specimens were dissected in the Anatomy Laboratory of this institution. The extension of the arcade, distance from the medial epicondyle, and relation with ulnar nerve were recorded. Results The arcade of Struthers was identified in 40 dissected arms (100%). In 29 (72.5%) the ulnar nerve was covered by a muscular arcade, in nine (22.5%) by an aponeurotic arcade, and in two (5%) the arcade was beneath the ulnar nerve. The extension of the arcade ranged from 3.0 to 7.5 cm, and the distance from the medial epicondyle ranged from 2.5 to 7.0 cm. Conclusion The arcade of Struthers is a musculoaponeurotic canal that represents an important site of entrapment or compression of the ulnar nerve. The arcade, the intermuscular septum, and the internal brachial ligament should be released in patients submitted to ulnar nerve anterior transposition surgery.

STRUTHERS’ LIGAMENT AND SUPRACONDYLAR HUMERAL PROCESS: AN ANATOMICAL STUDY AND CLINICAL IMPLICATIONS

ABSTRACT Objective: The objective of this study was to determine the frequency and anatomical characteristics of Struthers’ ligament and the supracondylar humeral process and evaluate the clinical implications in compressive neuropathy of the median nerve . Method: We dissected 60 arms from 30 cadavers (26 males and 4 females): 15 were previously preserved in formalin and glycerin and 15 were dissected fresh in the Anatomy Laboratory for this paper. The relationships between Struthers’ ligament and the median nerve and brachial artery and veins were documented with drawings and photos . Results: The supracondylar humeral process was not found in any of the 60 dissected arms. Struthers’ ligament was identified in six arms (two bilateral); in all cases high insertion of the pronator teres muscle was observed . Conclusion: Struthers’ ligament is an aponeurotic structure that may or may not be associated with the supracondylar humeral process, and is an important potential site of median nerve compression in the lower third of the arm. Level of Evidence IV, Case Series.